This invention relates to a process for producing enzyme cellulases by the fermentation of Trichoderma reesei (ATCC 26921) at elevated pressures and temperatures and an apparatus for high pressure fermentation.
A considerable quantity of cellulosic wastes and residues are continuously generated in the U.S. and elsewhere. For pollution abatement reasons and because these wastes represent an inexpensive source of biomass, it would be desirable to convert these cellulosic wastes into useful products. One proposal has been to convert cellulose in these wastes and residues into glucose by enzymatic hydrolysis.
A known source of enzymes that hydrolyse cellulose is Trichoderma reesei (ATCC 26921), a green mold. When fermented in a culture medium comprising a source of cellulose, this microorganism produces a potent extracellular complex of cellulolytic enzymes, e.g., Filter Paper (FP) cellulase, CMC cellulase and glucosidase, capable of effectively hydrolyzing crystalline cellulose to glucose. However, because a large amount of enzyme is needed, this method is only commercially practical if a relatively low cost method exists for the production of the enzyme.
Presently, most commercially significant fermentation processes are carried out in a batchwise manner under one atmosphere of pressure and at a temperature between 25.degree. C. and 60.degree. C. Such processes typically require days to complete, and the low yields and slow productivity are always under the constant threat of contamination. Moreover, such methods require a continuous supply of air and vigorous agitation in order to supply sufficient oxygen to the microorganisms.
In order to improve the productivity, efforts have been made to develop optimum strains of certain microorganisms (including T. reesei) using processes of mutation and selection. Although offering promise, these attempts have not provided a relatively inexpensive source of enzyme.